Semiconductor devices are manufactured by fabrication processes forming electric circuits on a semiconductor substrate, such as a silicon wafer. Metal features, such as copper (Cu) features, are deposited on the substrate to form the electric circuits. A barrier metal layer can be used to prevent the diffusion of copper ions into the surrounding materials. A seed layer can be subsequently deposited on the barrier layer to facilitate copper interconnect plating.
Traditional barrier layers, for example, Ta, Ti, TiN, TaN, etc., are expected to reach their workable limit at a feature size of about 20 nm. Barrier layers explored in recent years for use in small features as viable alternatives to traditional barrier layers include manganese-based barrier layers. For example, suitable barrier layers may include manganese (Mn) and manganese nitride (MnN).
Because of the contact potential between dissimilar metals (for example, a Mn barrier material and a Cu seed material), the electrode potential of the seed material barrier can shift, resulting in barrier dissolution and seed corrosion. Therefore, there exists a need for an improved electrochemical deposition process for reducing barrier dissolution and seed corrosion results. Embodiments of the present disclosure are directed to solving these and other problems.